ODE.
To solve the Ordinary Differential Equation (ODE), we use the Dormand–Prince method with a relative error tolerance of \(1e^{-2}\)  and an absolute error tolerance of \(1e^{-4}\) .
To support batch-wise processing in the ODE solver for the backward flow, we use the variant from OFlow [1]}. We also zero-pad the velocity network output to make it compatible with a ODE solver following OFlow [1]}.
